Support native deep-link auto-pairing for mobile and desktop

[rodriguezst]

Summary

Add support for opening the installed T3 Code mobile or desktop app from a pairing URL and automatically adding the environment, without requiring the user to open Environment Settings or manually enter connection details.

Example

Given the existing server pairing URL:

https://mydomain.com:3773/pair#token=TOKEN

Support a native wrapper such as:

t3code://pair?pairingUrl=https%3A%2F%2Fmydomain.com%3A3773%2Fpair%23token%3DTOKEN

The existing mobile QR parser already recognizes this general format, but opening it directly as an app deep link does not currently pair the environment.

Desired behavior

When a valid native pairing URL is opened:

1. Launch the T3 Code app, including from a cold start.
2. Handle the URL when the app is already running.
3. Parse and validate the existing HTTP(S) pairing URL.
4. Show the target host/environment and provide a clear pairing confirmation.
5. Register the environment using the existing onboarding flow.
6. Persist the environment in the client connection catalog.
7. Navigate to the connected environment after pairing succeeds.
8. Display useful errors for invalid, expired, consumed, or unreachable pairing URLs.

The flow should work on:

• iOS and Android.
• macOS, Windows, and Linux desktop.

[digitalbase]

Adding to this thread. I am willing to help out adding support for this (tried before #12311) but first we need agreement on direction and scope.

Here is our situation:

• we run t3.code (nightly now) within remote boxes for our dev team. These are 100s of t3 code instances
• all of these environments come with a t3 connection url + pairing code
• its the recommended flow (Theo videos) but then with a company shared pool (on kubernetes) of dev machines you can spin up

The instructions for developers are to:

1. copy the pairing url (generated on internal dashboard)
2. open t3
3. settings
4. go to connections
5. add connection
6. paste
7. exit connections

Step 2 to 8 can all be replaced by letting T3 handle t3code urls t3code://pair?host=<backend>&label=<name>#token=<credential>. A one-click add for a remote server/new t3 server instance.

Example of what my t3 looks like (40 remote envs):

[FrancisBourre]

+1, with a local-VM case and one addition: removing the environment again.

We run coding agents in local Linux microVMs on macOS, one per task, created and deleted throughout the day by a small manager app. Each VM runs t3 serve --host 127.0.0.1, the manager forwards that port to the host's loopback, and it mints a one-time link with t3 auth pairing create. It works well (Claude Code inside the VM, the desktop app on the host), but:

• every new VM means Settings → Connections → Add environment → paste;
• every deleted VM leaves a saved environment retrying in backoff until someone removes it by hand.

What would make this smooth for us:

1. Add: the pairing deep link proposed here. A confirmation dialog showing the host is fine.
2. Remove: a way for the tool that added an environment to forget it when the machine is deleted, like the "forget" link in Deep link to add or open a desktop-managed SSH environment #16981. Limiting removal to environments added through that path, for example with a "managed by" marker set at add time, would keep it from touching anything the user added.
3. Optionally, the same two actions through t3 app, which already talks to the running desktop app over its local control socket, so a local tool can do this without going through a browser. Whatever shape you prefer works for us.

I'm happy to help implement it once the direction and scope are agreed.